diff --git a/devel-docs/app/Makefile.am b/devel-docs/app/Makefile.am
index 322d12582b..94baf048b8 100644
--- a/devel-docs/app/Makefile.am
+++ b/devel-docs/app/Makefile.am
@@ -51,6 +51,11 @@ GTKDOC_CFLAGS = \
 	-I$(includedir)	\
 	-UGTK_DISABLE_SINGLE_INCLUDES
 
+if OS_WIN32
+else
+libm = -lm
+endif
+
 GTKDOC_LIBS = \
 	-Wl,-u,$(SYMPREFIX)xcf_init		   			     \
 	-Wl,-u,$(SYMPREFIX)internal_procs_init 				     \
@@ -101,7 +106,8 @@ GTKDOC_LIBS = \
 	$(DBUS_GLIB_LIBS)						     \
 	$(GEGL_LIBS)							     \
 	$(RT_LIBS)							     \
-        $(INTLLIBS)
+	$(INTLLIBS)							     \
+	$(libm)
 
 
 if ENABLE_GTK_DOC_APP